Electronic fingerprints for machine control and production machines

ABSTRACT

An electronic fingerprint measures a state of a machine and/or process. A controller controls movements of at least one component of the machine and a fingerprint device selects, for measurement, certain movements of the machine for generating an electronic fingerprint that that is representative of a condition of the machine tool or process.

BACKGROUND

[0001] Trace functionality in a drive or in automation system and traceselectable feedback or fixed parameters or process values, and allcontrol parameters to control the process is traceable. For example, itis normal the practice today to employ trace functionality to controlcurrents or motor currents. While trace functionality is used to set upthe machine, it is not being used to develop ideas to implement or bringabout new features in drive control, motion control or numeric control.It is not being used to describe the characteristics of the machine anduse these characteristics to improve the quality of the process orproduct.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0002] Within the meaning of the present specification, electronicfingerprints for a machine (eg. Machine tool or production machine) area set of measurements in a machine that are characteristic of anddocument the behavior of the machine. In machine control and productionmachines, every machine has variations in its behavior that make itunique. These unique behavioral traits are even diverse as even betweenmachines of the same type and character. That is, they could even be thesame model of machine. No matter how similar two machines are they willalways have some unique behavior that can be isolated and documented toidentify a condition of the particular machine. This is more true overtime, where operation of the machine may, and indeed does, alter theworking components of the machine or the alignment or the position ofits components, therefore, changing the behavioral characteristics ofthe machine. The set of behavioral characteristics that uniquelyidentify a particular machine are herein referred to as electronicfingerprints.

[0003] The present invention determines, for any particular machine,those set of characteristics that uniquely identify the condition ofthat machine. The novelty in the present invention is not only thefingerprints, but also the skill in knowing which measurements willresult in capturing the unique characteristics and which measurements tomake. That is, the measurements characterize the individualcharacteristic of the machine. Further, it is optimum to identify theminimum set of behavioral characteristics that identifies the particularmachine. In addition, the electronic fingerprints of the presentinvention are derived, such that, no matter how the fingerprint evolvesover time, a fixed fingerprint system is developed so that the machinecondition can be identified over time.

[0004] There are several advantages to employing electronicfingerprints. For one thing, it allows the operator to check theinstantaneous condition of the machine. Further, the changes of thebehavior of a machine can be compared to an initial state to a laterstate by certain measurements in the machine. The deviation compared tothe original state of the machine could be telling of the machinesperformance. The measurements may be repeated periodically to measurethe behavior of machines. This could also be used for predictivemaintenance by using the fingerprint to indicate a machine condition.

[0005] Now with reference to FIG. 1, the present invention provides anautomation component 10 that makes available mechanisms to determineelectronic fingerprints. The automation component may be, for examplepart of a machine tool or a production machine. Generally, there isprovided a controller (eg. PLC) for logic control 12 a and themechanical part that is driven by the controller (motion control ornumeric control)12 b. As an alternative one controller could do bothjobs (logic and motion control). There is further provided a userinterface 16 a that provides the user with an interface for monitor andcontrol of the automation component 10.

[0006] A separate user interface 16 b provides a user interface with anengineering system (setup, configuration, programming) for theautomation component. The user interfaces 16 a and 16 b might be runningon one HW-platform. In addition, remote access to, for example, a remotePC 18 through a communication channel 20, such as the Internet orIntranet, provided by an appropriate interface, TCP/IP or Ethernet, etc.An analysis 22 of the machine can be derived and displayed at the remotePC, for example. A machine data server (14) is linked to the automationcomponent. The present invention specifically provides means foridentifying the state of the machine and/or product, and a conditionthereof, by a fingerprint of the machine at a given time. The automationcomponents provide means for capturing fingerprints of the machine.

[0007] There are, of course, provided additional input/output signalsdepending on the type of machine controlled. Here, for example, there isprovided an input/output rack for inputting and outputting signals 24,such as those found on a programmable logical controller (PLC). There isalso provided an axis mechanism 26 which controls an axis of a movablepiece of the machinery, such as robotic arm, drill press, etc. Themachine may also be coupled to other processors, such as in acommunication network 28.

[0008] In order to obtain and analyze the fingerprints, the presentinvention provides a graphical user interface (GUI) 18. This may be, forexample, a human machine interface (HMI) that is modified according tothe present invention to lift, store and examine the fingerprints. Theinterface could be provided, for example, on a host PC and connected tothe automation component by a communication interface, such as, forexample the Ethernet or Internet. With the interface provided, thefingerprints can be evaluated manually or automatically according to theparticular description thereof set forth below.

[0009] As already indicated, part of the novelty of the invention is inknowing which measurements to make that will reveal the electronicfingerprint. The technique may vary according to type of machine. Forexample, machine tools having a cutting function can be caused toundergo a test trace function. However, other machines, such as a pumphave no trace capability. The invention includes various techniques,dependent on the type of machine, to develop, or “lift”, the electronicfingerprint. The recognition of the finger prints is realizable usingvarious techniques.

[0010] Fingerprint functionality can be implemented in the systemsoftware of the automation component 10. As already mentioned,electronic fingerprints can be realized concretely using an applicationof, for example, a trace test, for machine tools having a tracefunctionality with a numerical control. In another aspect, there isprovided in the automation component an easily programmable expirationoperational sequence. Using such application programs, the fingerprintscan be lifted. The automation component places suitable ApplicationProgram Interfaces (API) over from an application program to fingerprints to take up.

[0011] If the condition of the machine is the fingerprint and they arelifted using programming applications, the programming signals can bethought of as the “dust” with which the fingerprints are formed. Thesesignals may be, for example, internally accessible signals, which aresuitable, to document the quality of an expiration or a process.Thereby, the process specific parameters are defined. Also, any of themeasured values of drives, parameters from motion controllers,production machines or format data from the application program may beutilized.

[0012] In one example, the signal may be measured from distinguished,event-controlled signals that are generated cyclically or during acertain period. For another, the measured signals are derived from thecontrol and/or by control/application via auxiliary sensor technology.If necessary, the auxiliary sensor technology could include, forexample, acceleration meters.

[0013] As shown in FIG. 2a, the electronic fingerprint 30 of the presentinvention can be visualized as a two print. As shown by the parameterpoints 32, whose value is indicated by the position in the matrix 34,connected by the dashed lines 36. In this manner, it can be readily seenthat the electronic fingerprint of the present invention is similar toan actual fingerprint in the sense that it maps out an imprint that ischaracteristic of the machine from which the electronic fingerprint islifted. Of course, the fingerprint shown in FIG. 2a is anoversimplification, and can be expressed as a complex array of parameterpoints and may be an n-dimensional fingerprint displayed as a computergraphic.

[0014] As will be appreciated from FIG. 2. The condition of the machinecan be determined from the fingerprint. In FIG. 2b, for example, thereis shown a fingerprint that is unhealthy. Notice the deviation 38,illustrated by the arrow, which indicates a variance from the healthyfingerprint of FIG. 2a. The variance 40 can be thought of as the areaunderneath the portion of the fingerprint lying outside the healthyfingerprint. The fingerprints can be stored in advance in a database andlater compared. Also, unhealthy fingerprints can be collected over timeto form a database for future reference in other applications. With theelectronic fingerprints of the present invention, it will be instantlyrecognized that it is advantageous to analyze machines in this mannerbecause of the relevant ease in which deviations are identified. This isparticularly useful for user visual inspection of the fingerprints. In aglance, they can determine whether the machine is in an error conditionor not.

[0015] The fingerprint may be representative of a plurality of machinerelated states, including a machine behavior, for example. Thefingerprint may also be representative or product quality, which dependson both the machine and the material. In the example of FIGS. 2a and 2b, the fingerprint may indicate, in a laser cutting machine, the specialrelationship between speed of movement of laser and power. If, forexample, the relationship is not maintained at the correct fingerprint(FIG. 2b) the laser will move too slowly and burn holes in theworkpiece. On the other hand, the laser may move too quickly and wontcut the material. When the process is stable, as in FIG. 2a, then theproduct quality can be determined, i.e., the workpiece is cut properlyby the laser in our example.

[0016] As with any fingerprint, the electronic fingerprint is developedfor analysis, a sort of electronic sleuthing. As already described, theevaluation PC software runs an automated comparison/evaluation of thefinger prints. The results of which have wide application includingpreventing recognition of machine wear, quality assurance, maintenance,production data collection, error evaluation, documentation of theerror, delivery status, condition after software boot up andautomatically correcting errors. In error evaluation for diagnostics, inparticular, the finger prints can be derived when the machine isimproperly running. This is preferably achieved when the machine isrunning certain critical procedures, from which conclusions are tellingas to possible errors.

[0017] The building of the fingerprints can be achieved using thefollowing applications, for example. In the configuration in theengineering system, for example, there can be obtained the parametersfor the fingerprint. In configuration of the monitoring points, forexample, when it is configured which axis is to be controlled,parameters for control are sensed. Otherwise, the parameters may beobtained upon configuration of the observation parameters (e.g.situation layer, moment actual values, observer values, applicationvariables, etc.) The fingerprint parameters may also be developed fromthe parameters resulting from a start and stop event for recordingprojections or over application program control.

[0018] In another manner, the finger prints can be produced at thesoftware vendor end. This can be achieved by marking appropriateattributes of the relevant data/variables during programming of thesoftware. This is supported by the Engineering System (FIGS. 1, 16b) ofthe automation component. The measurements may be taken, for example,from the trace information. In addition, the vendor can provide for themeasurements along with the evaluation software for evaluation using theevaluation PC. There can be provided, for example, evaluation softwarefor comparison of the fingerprints. The application software, softwarefor finger print production (running in the automation component) andevaluation software (running in the evaluation PC) can be provided inany of the known, or equivalent, programming languages, including Java,for example.

[0019] There are various methods by which the fingerprint applicationcan be applied. In one method, the fingerprint application is downloadedthrough the PC communication connection to the machine, i.e., automationcomponent. Further, the application can be applied by deliberate machineservice personnel, via an external service branch. The fingerprintapplication could be automatically started by the application programitself. This could be automatically executed by the application, forexample, during certain maintenance or time intervals or duringreequipping procedures. Additionally, the fingerprint program may beimplemented by remote operation, for example, over the Internet. Also,the finger print measurement application can be supported optionally bya deposited workflow. It is also within the invention that the usermanually performs measurement of the fingerprints of the selectedmachine and causes the PC to note target/actual conditions, such ascyclically over a certain length of time, for example.

[0020] Like all fingerprints, the electronic fingerprints should beprofiled. The first step in profiling of the fingerprints is achieved bystoring the fingerprint in a suitable memory. In the machine/automationcomponent, for example, the fingerprint can be stored on Hard Disk orMemCard. Alternatively, the fingerprint can be stored on the data serverof the machine (FIGS. 1, 14), or on the evaluation PC, by remote file.The fingerprints may even be stored in additional machine informationstorage, such as production data or format information data.

[0021] Once stored, the profiling of the fingerprints continues with theevaluation process. This may take place in the evaluation PC and may beaccomplished either manually or automatically. From the results of theanalysis adjustments to the machine may be derived. Composites of“healthy” fingerprints may be stored in advance in the evaluationsoftware. These may be in the form, for example, of tolerances of thevarious machine components. With such an analysis capability, thefingerprints may evaluated or developed over time.

[0022] Now that the structure of the present invention has beendescribed, let us now turn to actual application examples employing theinvention. The following examples illustrate the operation of theinvention in regard to two types of machines, namely the productionmachine and the machine tool. In the former, the overall fingerprintingis concerned with the determination product quality and the machinequality or with both aspects. In contrast, the machine tool focuses ofthe determination of the machine quality, i.e., machine condition. Withmany measuring procedures there are overlapping effects between qualityof the processing material and machine quality and these examples are noexception. In any event, the following examples are so provided.

[0023] In the first example, a packaging machine is described. It isdesired, for example, to perform a pressure mark correction procedure,which corrects the pressure mark of the packaging machine. In thisinstance, measurements of the process are collated into an actual valueprofile. The same measurements can be derived from a fast pressure markcorrection, such as when a fast correction is driven out. The actualvalue profile changes can be compared over time. With such a comparison,the end product can be influenced directly.

[0024] In the same packaging machine, a real time view of the motion ofthe machine may also be viewed. Critical ranges in the total course ofmotion with a trace, for example, can be obtained. This could beperformed, for example, with welding seam such as in foil welding. Forexample, there may be measurement relevant parameters for the viewprocess. Or, the parameters measured may be the target values fromcontrol and drive. The measured values may also be actual values ofsensor technology or process variables from the application.

[0025] There is also provided a kind of test operation by application ofa test drive procedure for testing the machine. In the test operation, acyclic machine clock of the packaging machine with a defined productionspeed cycles through critical sections of the course of motion. Duringwhich time the present invention records the relevant actual values thattake place.

[0026] The above example is directed more to the operation of themachine. Here now is a injection moulding machine example where theemphasis is more on the quality of the product. Here, the injectingprocess for a certain tool is examined. With any given tool, there isnormally provided prescription data, such as the profile, temperatureattitude, etc. The prescription data is taken as the base fingerprintwhich is compared to actual data received over certain periods. The datais obtained from the injecting process from, for example, the manner inwhich the pressure or strength of the injection is applied. The valuesmay be compared, for example, using an integral based averagingalgorithm which is applied to values collected over a predeterminedperiod of time. From the measured variables, load differences and aginginfluences of the tool, for example, can be derived. With this data, thequality of the end product may be better influenced.

[0027] According to the foregoing description, a fingerprint for amachine tool or production machine may be derived to determine acondition of a machine or monitor the quality of the production machine.With the foregoing fingerprint parameters it is possible also totroubleshoot problems. In the following there is presented two simpleexamples where such machine problems can be pinpointed by fingerprintmeasurements. The main technique applied is to measure the fingerprintsperiodically and compare the deviations of the results with the initialmeasurements.

[0028] As shown in FIG. 3, there is graphically illustrated themeasurements obtained from an operation to change the periodic error inthe pitch of a ball screw. It is assumed, according to the example, thatthere is an axis X which is driven by a ball screw. In addition to themotor measuring system, there is also provided an additional linearscale along the axis X. The motor measurement system is used for theclosed loop control, whereas the linear scale is used as a measurementdevice during this measurement. If the axis is moved with a constantspeed along a certain travel area X₀, the ideal behavior is shown inFIG. 3.

[0029] The movement X(t) of the axis is ideal to demonstrate the valueof the invention, as inaccuracies during the production process of themechanical components of the machine are quite experienced in the actualworld. For instance, it is very often the case that a real ball screwexhibits a cyclic error in the pitch in comparison to the ideal. Due tomechanical forces, this error is magnified over a certain period oftime. This situation is shown in FIG. 5 wherein the cyclic errors in thepitch is shown enlarged and schematically. It may be, for example, thatthe error of the ball screw is enlarged after a certain time ofmachining due to mechanical forces

[0030] Now if the error exceeds a certain period of time, the ball screwshould be changed in order to avoid inaccuracies during machining. Theseerrors can be measured in the following way according to the presentinvention. In the first instance, the axis is moved with a constantspeed and only the motor measurement system is used for closed loopcontrol. In this case, the motor moves with a constant rotation speed.The constant speed yields to a constant rotation of the ball screw. Thepitch error is translates to the linear scale, where we have a periodicdeviation from the ideal behavior. This is apparent from the figures.

[0031] In FIG. 6, cyclic deviations of the signal of the directmeasurement system in case of cyclic pitch errors is shown where themotor measurement system is used for closed loop control. In this case,the more the errors in the pitch are enlarged, the more there is likelyto be deviations within the signal of the linear scale. At this time, ifthe axis is measured periodically in this way, it is possible to seecritical errors before workpieces are damaged. In other words, it iseither possible to change the ball screw, not after a fixed period oftime, but at a point in time before the critical state is reached or itis possible to change the compensation values for the pitch screw errorautomatically.

[0032] As shown in FIG. 7, in another example, backlash detection isdemonstrated. By means of the same method of the invention described, itis also possible to detect, for example, a backlash in a gear box. Abacklash may occur due to a build up of mechanical stresses. For thismeasurement, we move the axis forward and backward at a constant speed.Again, only the motor measurement system is used for closed loop controland the linear scale is used only for measurement purpose.

[0033] Ideally the X(t) behavior would be as it is shown in FIG. 7. Asshown, X(t) of the direct measurement system includes no backlash as theaxis is moved forward and backward at a constant speed. The influence ofbacklash on the measured signal, due to mechanical wear, for example,can be seen in FIG. 8. As will be seen, due to the backlash in thesystem, the axis does not follow immediately. This is particularlyapparent when the motor changes its rotation direction. At first, theaxis stays at its current position and then moves back with a constantshift.

[0034] From the fingerprint derived, it is apparent that the errors canbe determined earlier than when the critical state is reached andmaintenance can be applied before breakdown of the system. It ispossible, for example, to predict problems arising due to backlash byperiodically repeating the measurement and checking whether a pattern ofcritical deviation occurs in comparison to the initial state of themachine has been reached. In addition, it will be appreciated that thedegree of maintenance can be varied according to the fingerprint of thepresent invention. That is, there are degrees of unhealthiness of afingerprint and, depending on the degree, it may be determined thatmaintenance is not yet needed. On the other hand, the fingerprint may beemployed to determine minimum maintenance, deciding to allow the machineto continue to operate under less than optimum conditions, therebybetter managing the maintenance of a machine.

In the claims:
 1. A electronic fingerprint apparatus for measuring astate of a machine and/or process, comprising: an automation componentcomprising a controller for controlling movements of at least onecomponent of the machine or a portion of the process, wherein theautomation component provides means for capturing electronicfingerprints representative of the state of the machine and/or process;and a fingerprint device for selecting, for measurement, certainmovements of the machine for generating an electronic fingerprint thatthat is representative of a condition of the machine tool
 2. Theapparatus of claim 1, wherein the automation component is a numericcontrol, a motion controller, a programmable logic controller or anintelligent drive.
 3. The apparatus of claim 1, wherein the automationcomponent and the corresponding Engineering System provide a programplatform/environment for the implementation of electronic fingerprintsby an application engineer.
 4. The apparatus of claim 1, whereinapplicative implementation of the fingerprints is done by aconfiguration process in the engineering system and/or a programmingprocess using a specific API for the implementation of fingerprints. 5.The apparatus of claim 1, wherein the start of capturing the fingeprintsis done by one of the following actions selected from the groupconsisting of starting by local user via local HMI and starting byremote user via Ethernet/Internet and starting based on an eventevaluated in an application program running in the automation component.6. The apparatus of claim 1, wherein the apparatus is used for one ofthe following machines selected from the group consisting of a machinetool and a packaging machine and a rubber and plastics machine and apresses and printing machine and a wood machine and a glass machine anda ceramic machine and a stone machine and a textile machine and arobotics and a handling machine.
 7. The apparatus of claim 1, whereinthe fingerprint device and the automation component generate anelectronic fingerprint that is generic to a type of machine tool thatindicates a stable behavior of the machine tool.
 8. The apparatus ofclaim 2, wherein the fingerprint device and the automation componentgenerates an electronic fingerprint having a deviation from the stablebehavior, thereby indicating an unstable behavior of the machine.
 9. Theapparatus of claim 1, wherein the fingerprint device and the automationcomponent generates a specific fingerprint of a particular productionmachine that is representative of a state of an output of the particularproduction machine and/or the stable behavior of the machine.
 10. Theapparatus of claim 1, further comprising a graphical user interface fordisplaying a graphical depiction of the electronic fingerprint.
 11. Theapparatus of claim 1, wherein the fingerprint device has a capability ofgenerating a periodic electronic fingerprint that is developed from asnap shot of the state of the machine at a certain time.
 12. Theapparatus of claim 6, further comprising an application for comparingthe electronic fingerprints over time.
 13. The apparatus of claim 6,further comprising a memory for storing the electronic fingerprints as adatabase.
 14. The apparatus of claim 1, further comprising a maintenancescheduler for scheduling maintenance of the machine based on aprediction of a failure of the machine based on the electronicfingerprint.
 15. The apparatus of claim 1, further comprising a remotecommunication capability that couples the machine to a remote processor.16. The apparatus of claim 10, wherein the electronic fingerprint isdownloaded over the remote communication to the remote processor.
 17. Amethod for generating electronic fingerprints for measuring a state of amachine and/or process, comprising the steps of: selecting parameters ofat least one-component of the machine, for measurement, that isrepresentative of a condition of the machine; reading the parameters;and storing the read parameters, thereby creating an electronicfingerprint of the machine representative of the condition of themachine.
 18. The method of claim 17, wherein the step of selectingselects parameters that at a time when the machine is in a stable stateto generate thereby a generic type of electronic fingerprint thatindicates a stable behavior.
 19. The method of claim 18, wherein thestep of selecting selects parameters having a deviation from the stablebehavior, thereby generating an electronic fingerprint indicating anunstable behavior of the machine.
 20. The method of claim 17, whereinthe step of selecting selects parameters from a particular productionmachine that is representative of a state of an output of the particularproduction machine.
 21. The method of claim 17, further comprising thestep of generating a graphical depiction of the electronic fingerprint.22. The method of claim 17, further comprising the step of comparing theelectronic fingerprints over time.
 23. The method of claim 17, furthercomprising the step of scheduling maintenance based on the electronicfingerprint.
 24. The method of claim 17, further comprising the step ofremotely coupling the machine to a remote processor.
 25. A computerreadable product having encoded therein instructions for driving acomputer processor according to the steps of claim 17.